Direct wire connector for thermocouples



May 9, 1967 M. S. MOORE 3,319,215

DIRECT WIRE CONNECTOR FOR THEMOCOUPLES Filed April 12, 1965 n vlllllmYIIIIl/llllllg JAA/EMME MANUEL 5. Maa/e5 Zum, ,K2/MMM@ favmf/y rroeA/Ev United States Patent l 3,319,215 DIRECT WIRE CONNECT R FOR THERMUCOUPLES Manuel S. Moore, Northridge, Calif., assignor to Consolidated Controls Corporation, Bethel, Conn., a corporation of N. Mex.

Filed Apr. 12, 1965, Ser. No. 447,289 4 Claims. (Cl. 339-150) The present invention relates to electrical connectors and, more particularly, to a new and improved thermocouple connector arrangement whereby direct wire connections to the thermocouple can be readily and easily made.

In thermocouple arrangements heretofore proposed, diiiiculties have been experienced in providing a suitable connector to which external lead wires may be readily attached without introducing measurement errors. Since the wires utilized to form the actual thermocouple junction are usually of dissimilar metals, the conventional male-female connector arrangements, such as are normally used in household wiring circuits, are unsatisfactory because they introduce further junctions of dissimilar metals which produce errors in the thermocouple measurement. Furthermore, these conventional connector arrangements are unsuitable because, in general, they require the use of tools to make connections to screw-type terminals and the like. While certain arrangements have been heretofore proposed for direct wire connections, these arrangements `are not suitable for thermocouple applications because they introduce further junction errors and also because the arrangement employed to grip the bare wire introduces further shunting errors due to spring biasing elements and the like.

It is, therefore, an object of the present invention to provide a new `and improved thermocouple connector arranged for direct wire connection thereto, wherein one or moe -of the above discussed disadvantages of the prior art is eliminated.

Another object of the present invention is the provision of a new and improved connector for use with thermocouple lead wires of selected materials wherein junctions between dissimilar metals are avoided.

Yet another object of the present invention is the .provision of an electrical connector of the type described including means for positively connecting a wire to a conducting member of the connector in a manner whereby the connection is not shunted by other parts of the connection.

Still another object of the present invention is the provision of a new and improved connector for use in direct connected precision thermocouple systems wherein a` thermocouple lead wire is connected to a conducting member of the connector and positively is held in place by a locking dog engaging the wire over a relatively small area, thereby reducing the posibility of errors in the systern. Y

Another object of the present invention is the provision of a new and improved direct wire thermocouple connector which is small, lightweight, easy to operate, and relatively low in cost.

Another object of the present invention is the provision of a new and improved connector of the type described for use with a pairY of thermocouple leadsV of dissimilar material in which the respective leads are secured to conducting members of like material to reduce errors in the system.

For a better understanding of the present invention reference should be had to the folowing detailed description taken in conjunction with the drawings, in which:

FIG. `1 illustrates a connector constructed in accord- 3 ,3 19,2 l 5 Patented May 9, l 967 ance with the present invention as utilized in connection with a thermocouple system;

FIG. 2 is a tranverse sectional view of the connector taken substantially -along Alines 2 2 of FIG. 1;

FIG. 3 is a transverse sectional view of the connector taken substantially along lines 3--3 of FIG. 1;

FIG. 4 is a longitudinal sectional view of the connector taken substantially along lines 4 4 of FIG. 2;

FIG. 5 is an enlarged fragmentary sectional view similar to FIG. 4, illustrating a locking dog of the connector in one of its -operative positions;

FIG. 6 is an enlarged fragmentary sectional view similar to FIG. 5, illustrating the locking dog of the connector in another of its operative positions; and

FIG. 7 is an exploded view of the connector of FIG. l, illustrating the various parts thereof.

Brieliy, the foregoing and other objects and advantages of the present invention are accomplished by the provision of a new and improved thermocouple connector assembly comprising a body of insulating material and a pair of conductive members mounted in said body :and having tubular wall portions forming sockets, each with an open end for receiving the end of one of a pair of bare thermocouple lead wires. Locking dogs for holding the wires in said sockets are pivotally mounted on said body and each includes a wire-engaging portion which extends through an opening provided in the wall portion of the adjacent socket. The locking dogs are biased to hold the 'wires firmly against the socket walls by spring biasing means which is insulated from the conducting member except through the relatively `small area of engagement of the dog with the lead wire. Also, the sockets themselves are made of the same material as the corresponding thermocouple and lead wires so that no dissimilar metal junctions are produced and no shunting effect is produced by the spring biasing means while at the same time providing a quickly assembled direct wire connector arrangement for thermocouples.

Referring now to the drawings, there is illustrated a connector assembly 10 constructed in accordance with the features of the present invention. The assembly 10 includes a body member 12 of insulating material constructed in two separate parts or halves 14 and 16 (FIG. 7). The parts 14 and 16 are almost identical and are formed with irregular faces 14a and 16a, respectively, having portions thereof which contact or face one another.`

on assembly of the parts to f-orm the completed body. Specifically, the face 14a of the part 14 includes` a planar central surface 14b extending the length of the body, a pair of outer surfaces 14e spaced on opposite sides-of the central portion. and lying in a first common plane therewith and a pair of relatively small outer surfaces |14d adjacent the ends of the surfaces 14o and disposed to lie in a second common plane outwardly parallel of the rst common plane. The face 16a of the part 16 includes. a similar group lof surface 16h, 16C, and 16d, respectively, and when the parts 14 and 16 Iare assembled together,

the surfaces 14d and 16d are in confronting contact with one another while the group of coplanar surfaces 14b and 14C of the part 14 and the similar group of surfaces 16b and 16e of the part 16 are in spaced-apart, parallelfacing relationship forming a pair of enlarged open spaces |15 therebetween (FIGS. 2 and 3).

The face 14a of the part 14 is formed with a pair of recesses 14e extending longitudinally thereof and spaced in parallel relation to each other along opposite edges of the central surface 14b and between the two outer su-rfaces 14C. The part 16 is provided with similar recesses 16e land when the parts 14 and 16 are assembled together, as described, the recesses 14e face the recesses 16e and define therewith opposite sidewalls of `a pair of paralle'l 3 bores which extend longitudinally through the assembled body 12.

The bores forme-d by the recesses 14e and 16e carry a pai-r of elongated contact mem-bers 118 and 20 formed of conducting material, and these members are held in place against longitudinal movement within their respective bores by means of pins 22 which extend transversely throug-h apertures 18a and 20a, formed in the respective contact members. Opposite ends `of each of the pins 22 extend into the respective parts 14 and 16 when assembled together and are seated in small openings or keyholes 14]c and 161, thus keying the members 18 and 20 against longitudinal movement with respect to the assembled body 12.

Preferably, the contact members 18 and 20 are disposed to extend completely through the assembled body 12 so that connections can readily *be made to the opposite ends thereof, and, as illustrated in FIG. 4, the right-hand ends of the members 18 and 20 protrude slightly from the right-hand end of the body 12 while the left-hand ends of the members are approximately ilush lwith the left-hand end of the body. The left-hand end portions of the members 118 and 20 are formed with hollow tubular wall sections 18]; and 2Gb, respectively, to deline open-ended sockets 18C and 20c for receiving the ends of a pair of lead wires 24 carried together in a common jacket 26. The stripped ends Iof the wires 24 are directly inserted into the open ends of the respective sockets, as illustrated in detail in FIGS. -and 6, to make connection between the wires and the respective contact members 18 and 20.

The tubular wall Iportions 1812 land Ztlb of the contact members are provided with oppositely facing, longitudinally extending slots 18d and 20d, respectively, and these slots communicate with the interior of the respective sockets 18b and 20b and are spaced from the open ends thereof. In addition, the slots 18d and 20d are aligned to face oppositely outwar-d for communication with the respective open spaces between the assembled parts 14 and 16.

A locking dog 28 is mounted in each of the respective open spaces 1-5 between the :assembled parts 14 and 16 for pivotal movement about one of a pair of mounting pins 30 disposed outwardly of the respective contact members 18 and 20. The pins 30 extend transversely between the assembled parts 14 and 16, and opposite ends thereof are seated within recesses or keyholes 14g and 16g formed in the parts.

'Iihe locking dogs 28 are formed to include manual release arms 28a extending outwardly from the assembled body 12 in order that a person may conveniently grasp the outer ends :for releasing the dogs. The dogs 4are formed with wire-engaging portions 28b adapted to move Within the slots 18d and 20h of the respective contact members in order to engage the wires 24 inserted in the pockets and prevent the wires from being extracted or pulled out. The wire-engaging portion 28b of each dog includes a curved edge surface 28e having serrations or teeth formed thereon to bite into the wire inserted into the socket, and the curved edge is formed about an axis eccentric of the pivot pin 30 so that forces applied on the wires tending to pull them from the sockets will also tend to pivot the dogs about their respective pivot pins in a direction causing the serrated edges 28C to bi-te deeper into the wires, thereby increasing the holding power. As an example, referring to FIG. 5, when a wire 24 is inserted into t-he socket 18h it will engage the serrated edge 28e` of the dog 28 causing the dog to pivot in a clockwise direc-tion to the engaged position illustrated in solid lines in FIG. 6. In the engaged position, the Wire cannot be readily pulled out of the socket because a pulling force on the wire will tend to pivot the dog in a counterclockwise direction, resulting in the serrated edge or teeth 28C biting more ldeeply into the wire and thereby increasing the transverse holding force of the dog exerted against the wire and socket. Because the serrated edge 28C is curved about an axis eccentric of the pivot pin 30, movement of the dog in a counterclockwise direction causes the edge to move `farther inwardly into the socket, and the dog is thus self-locking.

In order to release a dog 28, once it is in a wire-engaging position, as shown in FIG. 6 (solid lines), the outer end of the release arm 28a is manually moved in the direction indicated by the arrow 32, causing the dog to pivot in a clockwise direction about the pin 30 to a released position (dotted lines), wherein the serrated edge 28C moves out of engagement with the wire. Once the dog is moved to the manually released position, the Wire can be readily withdrawn from the socket. The slots 18d and 20d are dimensioned to permit free movement of the wire-engaging portions 2817 of the dogs into and yout of engaging contact with wires inserted in the sockets and accordingly, Wires of various diameters inserted in the sockets can be held rmly against the socket wall by the generally transverse forces applied by the dogs. Additionally, stranded-type wires can be accommodated as well as solid types because the dogs act in a generally transverse direction in respect to the sockets and hold the wires against Wall portions generally opposite, or closely adjacent, the elongated slots 18d and 20d.

In order to continually bias the locking dogs 28 into wire-engaging position, as shown, for example, in solid lines in FIG. 6, and to bias the dogs into the position of FIG. 5 when a wire is not present in the socket, each dog includes a bias lug yor `arm 28d which is in continual engagement -against the free end of one of a pair of biasing sp-rings 34. The springs '34 extend toward the left-hand end (FIG. 4) of the assembled body within the open spaces 15 lbetween the parts 14 and 16 and are disposed `outwardly of the respective contact members 18 land 20 and are generally parallel thereto. The biasing springs 34 are supported in a cantilever fashion with their xed ends insulated from the members 18 and 20 and seated within aligned facing recesses 14h and 16h formed in the contacting surfaces 14d and 16d of the parts 14 and 16. In order to prevent the springs 34 from moving longitudinally within the recesses 14h and 16h, the xed end of eac-h spring is formed with a short tang or dog extending perpendicular to the elongated main portion of the spring for seating Within la short keyhole, lsuch as the keyhole 161 which extends downwardly into the part 16 (FIG. 7) from the right-hand end of each recess 16h therein. The free ends of the springs 34 are in continual biasing engagement with the bias arms 28d of the dogs, 'urging the ldogs to pivot about their respective mounting pins 30 into a wire-engaging position, as shown, for example, in solid lines in FIG. 6. If Wires are not present in the socket, the springs will bias the dogs -into the position shown in FIG. 5, wherein the dogs extend `further into the sockets awaiting engagement with wires inserted therein. When manually -releasing the dogs it is necessary to overcome the biasing force of the springs and when such manual pressure is released, the springs insure that the dogs do not remain in the released position (dotted lines, FIG. `6).

Because the fixed ends of the springs 34 are mounted in remote insulated relation with respect to the contact members 18 and 20, the springs may be constructed of any good spring material even though the spring material is dissimilar to the contact members or thermocouple lead wires because there is no shunting around the contact area between the wires and their respective sockets formed by the springs. This is especially important in thermocouple circuits wherein shunting around the contact areas between a lead and its contact member with dissimilar materials could result in errors in the thermocouple system. As previously discussed, each one of the pair of thermocouple leads is generally of a dissimilar material from that of the other and, accordingly, the contact members 18 and `20 are constructed of materials like that of the wires they receive and can be color coded to insure that proper connections are made. The dogs 28 can be constructed of materials dissimilar to that of the lead wires 24 because only a relatively small portion of the serrated edges 28e thereof are in contact with the wires and the effect of a junction of dissimilar materials between the dog and the Wire engaged thereby is negligible in view of the relatively large area of contact between the wire and the sidewall of its receiving socket. Even though the dogs are in contact with the springs 34, which may be of different material from that of the dogs, the effect is negligible because the fixed ends of the springs are insulated from the contact members 18 Iand 20 and no shunt circuit is formed by the dogs and the respective springs in contact therewith.

When the parts 14 and 16 are assembled together, the pins 22, pins 30, and contact members 18 and 20 all serve as additional spacing elements to insure the proper spacing between the surfaces 14b, 14e, and the surfaces 16b and 16C.v The parts 14 and 16 are assembled with the pins, contact members, springs, and dogs in their respective positions therein, and are held together in assembled position by means yof an outer jacket 36 which is slipped onto the right-hand end of the assembly to iit around recessed portions 14]' and 16]' provided in the outer surfaces of the respective parts. The jacket 36 is held in position on the assembled parts and the parts are additionally held together by means of a rivet or pin 38 which extends through the parts and jacket and is upset or headed on opposite end, as illustrated in FIG. 3.

Prior to the assembly of the jacket 36 with the body 12, the jacket is slipped over the end of another electrical cable 40 which includes a pair of wires 42. In thermocouple installations, preferably, the Wires 42 are constructed of material like that of the wires 24 and their respective contact members 18 and 20 of the lconnector to avoid the problem of junctions of dissimilar materials. The ends of the wires 42 are xedly connected to the right-hand ends (FIG. 4) of the respective contact members 18 and 20 by soldering, as shown, or by other suitable means, such as swaging, 'and it is preferable that these connections likewise do not involve junctions of dissimilar materials, for the reasons previously discussed. If it is desired to provide releasable connections between the connector and the cable 40, it is Within the scope of the present invention to provide socket-type connecting apparatus .adjacent the right-hand portion of the c-onnector, similar to that of the left-hand portion described herein, and when such apparatus is provided, the resulting connector might be more aptly described as a splice connector for use in the direct splicing of electrical leads.

When connecting the wires 24 of the cable 26 with the connector 10, an outer protective jacket 44 may be utilized to enclose the left-hand end of the assembly, as indicated in FIGS. 1 and 4. The jacket 44 is preferably constructed of ilexible material, `such as rubber or plastic, and is slipped onto the end of the cable 26 before connection ofthe wires 24 is made.

After the wires are inserted into the respective sockets of the connector, the flexible jacket 44 is then slipped into position enveloping the body 12 to enclose the region adjacent the left-hand end. The jacket is provided with a beaded portion 44a for holding it in position .and can only be removed by peeling or pulling the beaded portion leftwardly until clear of the body 12. When it is desired to remove the wires 24 from connection with the sockets, the tips of the release arms 28a are pinched toward one another, causing the dogs to move to the released position wherein the wires 24 can be extracted from the sockets. No tools are needed to make or break connections between the wires 24 and the connector 10,

and no special preparation of the wires is needed other than stripping back a short portion of insulation from the ends thereof if insulated wires are utilized.

The connector 10 is small, light in weight, easy to use, and relatively inexpensive, and can be utilized in many dilerent types of installations or systems. When used in thermocouple systems, contact members constructed of material similar to the material of the lead wires can be used and, because there is no shunting of the connections between the wires and contact members, the

material of the locking dogs and bias springs is not critical. The connector can be easily assembled in the field and a supply of contact members constructed of commonly used materials ycan be carried so that a connector can be made up especially for a given installation.

While there has been illustrated and described a single embodiment of the present invention, it will be apparent that various changes and modifications thereof will occur to those skilled in the art. It is intended in the .appended claims to cover all such changes and modications as fall within the true spirit and scope of the present invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A connector assembly for direct connection to a pair of thermocouple lead wires of dissimilar materials, said assembly comprising a body of insulating material formed in two parts, each part including a pair of side-by-side recesses formed in a face thereof, said parts being assembled together in facing relation wherein the recesses on one part cooperate with the recesses on said other part to form a pair of conducting member receiving bores extending through said body, a pair of conducting members carried in said bores, each member including a tubular wall portion forming a socket with an open end for receiving one of said Wires, said members being formed of the same materials `as the thermocouple lead wires, a pair of locking dogs pivotally mounted on said body loutwardly of said conducting members, each of said dogs including a wire-engaging portion movable within an opening formed in the tubular wall of the socket of one conducting member between a released position and a wire-engaging position for holding the end of a wire in said socket, and biasing means spaced from said members for biasing said dogs into wire-engaging position.

2. Apparatus as dened in claim 1 wherein said biasing means includes a pair of spring members, each mounted outwardly of a respective conducting member, each of said spring members having a lixed end mounted in said insulating body and spaced from the open end of the respective conducting member and having the free end thereof extending between said faces to engage one of said dogs.

3. Apparatus as dened in claim 1 wherein each of said dogs includes a manual release arm protruding from said body for moving said dogs to said released position, said arms positioned on opposite sides of said sockets for movement toward one another to release said dogs.

4. Apparatus as defined in claim 1 wherein the wireengaging portion of each dog comprises an arcuate serrated gripping edge eccentric of the pivotal mounting thereof for biting engagement transversely into the lead wire inserted in a socket.

References Cited by the Examiner UNITED STATES PATENTS 1,526,265 l2/ 1925 Bergman 339-274 X 1,960,191 5/1934 Staub etal 339-274 X 2,799,009 7/ 1957 Benander 339-95 X 3,249,906 5/ 1966 Stillmaker 339-176 X EDWARD C. ALLEN, Primary Examiner.

W. DONALD MILLER, Examiner. 

1. A CONNECTOR ASSEMBLY FOR DIRECT CONNECTION TO A PAIR OF THERMOCOUPLE LEAD WIRES OF DISSIMILAR MATERIALS, SAID ASSEMBLY COMPRISING A BODY OF INSULATING MATERIAL FORMED IN TWO PARTS, EACH PART INCLUDING A PAIR OF SIDE-BY-SIDE RECESSES FORMED IN A FACE THEREOF, SAID PARTS BEING ASSEMBLED TOGETHER IN FACING RELATION WHEREIN THE RECESSES ON ONE PART COOPERATE WITH THE RECESSES ON SAID OTHER PART TO FORM A PAIR OF CONDUCTING MEMBER RECEIVING BORES EXTENDING THROUGH SAID BODY, A PAIR OF CONDUCTING MEMBERS CARRIED IN SAID BORES, EACH MEMBER INCLUDING A TUBULAR WALL PORTION FORMING A SOCKET WITH AN OPEN END FOR RECEIVING ONE OF SAID WIRES, SAID MEMBERS BEING FORMED OF THE SAME MATERIALS AS THE THERMOCOUPLE LEAD WIRES, A PAIR OF LOCKING DOGS PIVOTALLY MOUNTED ON SAID BODY OUTWARDLY OF SAID CONDUCTING MEMBERS, EACH OF SAID DOGS INCLUDING A WIRE-ENGAGING PORTION MOVABLE WITHIN AN OPENING FORMED IN THE TUBULAR WALL OF THE SOCKET OF ONE CONDUCTING MEMBER BETWEEN A RELEASED POSITION AND A WIRE-ENGAGING POSITION FOR HOLDING THE END OF A WIRE IN SAID SOCKET, AND BIASING MEANS SPACED FROM SAID MEMBERS FOR BIASING SAID DOGS INTO WIRE-ENGAGING POSITION. 